A lithium-ion battery (LIB) converts chemical energy into electrical energy through a redox reaction between cathode and anode. Lithium is the lightest among all metals and has a very low electrochemical potential (-3.04V vs. standard hydrogen electrode), so LIB has a very high specific energy density. Despite these advantages, safety issues of LIBs should be solved and higher energy density must be achieved. Therefore, we develop advanced materials to improve electrochemical performance and safety.

Aqueous Zn-ion batteries or hybrid capacitors are considered as great candidates for grid-scale energy storage systems. Zn has low redox potential (-0.76 vs. standard hydrogen electrode), high theoretical capacity (~820 mAh g-1 and ~5833 mAh L-1), and high environmental friendliness. Moreover, the use of aqueous electrolytes guarantees high safety during long-term cycling. Our research aims to develop or modify electrode materials and introduce novel strategies to overcome current problems such as corrosion or dendrite formation of metallic Zn and narrow working voltage.

The seawater battery (SWB) is a promising next-generation battery system. With unlimited seawater, SWB is free from resource shortage problems, which is an emerging problem in conventional Li-ion battery systems. Moreover, because it is operated in aqueous seawater, the effective heat transfer can be realized, preventing fire or explosion of cells. This safe, cost-effective and environmentally benign system would open a new era to the energy storage field. We investigate the advanced electrode materials for SWB, which is necessary for achieving practical application of SWBs.